Plastic board forming device



March 31, 1936. Q s 2,035,495

PLASTIC BOARD FORMING DEVICE Filed April 27, 1954 2 Sheets-Sheet 1 INVENTOR CLAUDE B.Mu s.

ATTORNEY C. B. MILLS PLASTIC BOARD FORMING DEVICE March 31, 1936.

Filed April 27, 1934 2 Sheets-Sheet 2 INVENTOR CLAUDE B.M|u s.' ML 6 AT.TORNEY r L.J I

Ill

Patented Mar. 31, 1936 UNITED STATES PATENT OFFICE 2.035.495 PLASTIC nosan romumc DEVICE Claude B. Mills, Port Clinton, Ohio, assignor to United States Gypsum Company, Chicago, 111., a corporation of Illinois Application April 27, 1934, Serial No. 722,624

8 Claims. (Cl. 154-1) board forming device which will produce a perfectly square edge on the board without producing any waves in the flat surfaces of the board; also 15 to improve board forming devices in other respects hereinafter specified and claimed.

Reference is to be had to the accompanying drawings forming a part of this specification, in which Fig. 1 is a plan sectional view showing my improved board forming device,

Fig. 2 is a transverse sectional elevation through the board forming device taken on line 2-2 of Fi 1.

Figs. 3 and 4 are longitudinal sectional views through the device taken on lines 3-3 and 4--4 of Fig. 1 respectively, and

Fig. 5 is a transverse sectional view through a gypsum board made by the use of my forming device.

In the making of plastic boards, such as those made with a core III of gypsum or other cementitious material, and paper cover sheets I I and I2, it is customary to fold the lower cover sheet ll about the edge of the core to form a fold l 3 which is then folded inwardly at the top surface to form a flap l4. The outer edge of the top cover sheet I2 is provided with a chamfer l5 which reduces the thickness at the edge to practically a knife edge, and this chamfered edge I5 is attached to the flap l4 by means of glue or other adhesive material l8. Score marks I! are formed in the paper cover sheet I I adjacent each edge of the fold I! so as to permit the cover sheet to bend sharply at the corners and thus produce a square edged board. It has always been a dlmcult problem to shape the edge of the board during its manufacture so that the board edge is perfectly square and so that both surfaces of the board are perfectly flat, owing to the soft plastic condition of the core material Ill, and the forming device disclosed in this application accomplishes this forming of the board edge in a manner surpassing that of any device heretofore proposed.

The gypsum board is manufactured by depositing the plastic core material l between the two cover sheets II and I2 behind a master roll which supplies the upper cover sheet l2. Suitable folding devices, not shown, are used for folding the fold l3 and the flap l4 about the edge of the core material Ill. The lower cover sheet H is supported upon a conveyor l 8, preferably in the form of a wide flexible belt, and said conveyor is supported on a plurality of transverse rollers l9 which are rotatably mounted in bearings 20 at each end thereof. A longitudinal frame angle or other frame member 2| supports the bearings 20 and in turn is supported on vertical standards 22 which form part of the frame work of the machine.

My improved board forming device comprises a transversally extending channel 23 having a horizontal web 24 and vertical flanges 25. A plate 26 of plate glass or other suitable material is cemented to the bottom surface of the channel web 24. The bottom surface of plate 26 is provided with bevelled edges 2'! and is arranged to press firmly against the upper cover sheet l2 during the continuous movement of the plastic board so as to iron out any undulations in the top surface of the board and thusproduce a perfectly flat upper surface. The plate 26 also serves to cause the chamfered edge l5 to seal tightly against the flap it through the action of the adhesive it.

In order to permit the vertical movement of the channel 23 and plate 26 into and out of operative contact with the cover sheet I2, I provide slots 28' in the standard 22 which are adapted to receive outstanding studs 29, one of said studs being attached to each end of the channel web 24. A shaft 30 is rotatably mounted at each end in a slot 3| which is formed in the standard 22. An eccentric cam 32 is secured to each end of the shaft 30 adjacent the standard 22, each cam being supported on an outstanding angle shelf 33 secured to the standard 22, as by rivets 34. An operating lever 35 is secured to each end of the shaft 30 adjacent the cam 32 so as to permit the shaft 30 to be rocked through 180 in order to elevate the shaft 30 in the slot 3|. A pair of chains 36 is supported near each end of the shaft 30 by a link 31 embracing said shaft. The lower ends of the chains 36 are secured by hooks 38 to the upstanding flanges 25 so that when lever 35 is rocked through 180, the channel 23 and plate 26 are raised or lowered, as the case may be.

It is important that edge forming devices be caused to operate on the edges of the board during, before and after the action of the smoothing plate 26 so as to insure the production of perfectly square edges, together with a flat upper surface of the cover sheet l2. For this purpose, I provide an edge forming bar 40 at each edge of the plastic board, each of said bars 40 extending immediately below the smoothing plate 25. A plate 4| extends inwardly over the top surface of the cover sheet, the outer ends of the plate 4| being secured to the ends of the edge forming bars 40. The bracket 42 is secured to each end of the bars 40 on top of the plate 4|, each of said brackets 42 having a slot 43 for slidably receiving a transversally extending slide bar 44 which extends across the machine. Bolts 45 serve to connect the brackets 42 to the bars 40. Each of the bars 44 is movably connected at the center thereof by a slidable and adjustable bolt 46 to a bar 41 which extends transversally across slots 48 in channel flanges 25. Angle brackets 45 are slidably associated with the channel flanges 25 on each side of channel 23, and bolts 50 serve to rigidly connect the bar 41 to said brackets 49. A pair of stop bars are secured by bolts 52 to one of the bars 44 on the following side of the machine, intermediate the ends of said bar 44. The forward ends of the bars 5| bear against one of the flanges 25 so as to maintain the edge forming bars in proper aligned position relative to the smoothing plate 26. Compression springs 54 are confined on the outer ends of the bars 44 between the brackets 42 and washers 55 held in position by pins 56, so as to resiliently urge the edge forming bars 40 tightly against the edges of the board and thus produce perfectly square edges. Additional pin holes 51 are provided in the bars 44 spaced apart from the ends thereof so as to receive pins 56 when it is desired to make a narrow width board.

I would state in conclusion that while the illustrated examples constitute practical embodiments of my invention, I do not wish to limit myself precisely to the details illustrated, since manifestly, the same may be considerably varied without departing from the spirit of the invention as defined in the appended claims.

Having thus described my invention, I claim as new and desire to secure by Letters Patent:-

1. In a plastic board forming device, a smoothing plate arranged to press against the top surface of the board during the movement thereof, board edge forming means associated with said smoothing plate, and means for moving said smoothing plate out of contact with said board together with said edge forming means.

2. In a plastic board forming device, a smoothing plate arranged to press against the top surface of the plastic board during the movement thereof, an edge forming bar extending across each end of said smoothing plate, and resilient means :gapted to press said bars against said board 3. In a plastic board forming device, a smoothing member arranged to press against the top surface of the plastic board, during the movement thereof, a slide bar extending substantially parallel to said smoothing member, and an edge forming device slidably mounted .on said bar and adapted to yieldingly press against the edge of said board adjacent each end of said smoothing member.

4. In a plastic board forming device, a smoothing member arranged to press against the top surface of the board during the movement thereof, board edge forming means associated with said smoothing member, and cam means for raising and lowering said smoothing member relative to said board.

5. In a plastic board forming device; a channel strip extending across the upper surface of said moving board, a smoothing plate of non-metallic material secured to the web of said channel strip and yieldingly pressing against the upper surface of said board, means for moving said strip and plate in a substantially vertical direction,- guide means for permitting vertical but not horizontal movement of said plate, and edge forming means associated with each end of said plate and adapted to yieldingly press against the edges of said moving board.

6. In a plastic board forming device, a smoothing member arranged to press against the top surface of the board during the movement thereof, an edge forming bar extending across each end of said member and engaging opposite edges of said board, and spring means associated with each end of each of said bars for resiliently pressing said bars against said board edges.

7. In a plastic board forming device, a smoothing member arranged to press against the top surface of the board during the movement thereof, an edge forming bar extending across each end of said member and yieldingly engaging opposite edges of said board, and inwardly extending plates associated with each end of said bars, said plates being arranged to press against the top surface of said board adjacent the edge thereof.

8. In a plastic board forming device, an elongated smoothing member extending across said board and arranged to press against the top surface thereof during the movement of said board, edge forming means associated with the ends of said smoothing member, a transversely extending shaft rotatably supported above said member, chains supporting said smoothing member on said shaft, and cam means for raising and.

lowering said shaft and smoothing member when said shaft is rotated.

CLAUDE B. MILLS. 

